SandForce PCI-E SSD Anatomy

The SandForce SF-1200 SATA-3GBps controller is a durable component. SandForce features DuraClass technology on their SF-1200 processor, which claims to provide best-in-class endurance, performance, and lower power consumption. DuraWrite technology extends the endurance of MLC-NAND memory by providing at least five year lifecycles measured with 3000-5000 cycle MLC flash. Additionally, SandForce RAISE technology provides RAID-like protection for single SSD computer systems, and data is secured with AES-128 automatic encryption.

It's easy to mistake the OCZ RevoDrive X2 as merely having four SandForce SF-1200 SSDs combined into RAID-0, which oversimplifies things. There are two primary components to the average SandForce-driven SSD: a single storage controller and flash memory. The OCZ RevoDrive X2 is comprised of four primary components: PCI-Express bridge, RAID controller, dual storage controllers, and flash memory. Some might consider these differences minor semantics, but in truth they contrast a simple storage device (SSD) against a more complex RAID system on the PCI-Express platform.

The first evidence that this isn't your average SSD comes when you boot-up the computer and are given the opportunity to enter the Silicon Image RAID Configuration Utility. Since the SiI3124 chip used on RevoDrive series is identical to those used on many desktop motherboards and RAID controllers, users will find it very familiar. The OCZ RevoDrive has two 'drives' permanently attached, so many of the RAID options are available but unusable (RAID-5/10). Users can destroy the RAID set and rebuild it using smaller or larger stripe sizes, although our SandForce SF1200 RAID-0 SSD Performance article has demonstrated that larger stripes are better for SSDs.

Silicon Image SiI3124 RAID Configuration Utility

When the OCZ RevoDrive X2 SSD is installed into a Windows 7 (64-bit) computer system as a secondary drive, the device manager prompts for driver installation which indicates a lack of Plug-n-Play compliance. OCZ includes the necessary SiI3124 drivers with the RevoDrive series SSD kit, as well as their website. As of November 2010 these drivers were identical to the latest package available direct from Silicon Image (si3124r5_15230_x64_Logo).

Windows 7 Device Manager

SandForce-driven SATA SSDs are capable of connecting to various controller hosts, such as those from Marvell or Intel, which retain TRIM garbage collection functionality as well as AHCI mode features. SandForce-driven PCI-Express form factor devices have their own host controller, and lose this functionality as a result. This is why the SandForce PCI-E SSD anatomy becomes important to understand.

The Pericom PI7C9X130 PCIe-to-PCIx reversible bridge chip is straight-forward in purpose and functionality, as it connects the PCI-Express x4 port to one standard 64-bit /133 MHz PCIx port which messages the Sil3124 RAID controller chip. This is where the magic happens, as Silicon Image defines their SiI3124 chip as a PCI-Express to SATA-3GB/s controller capable of driving four ports. The current version of OCZ's RevoDrive X2 SSD incorporates the Sil3124 chip to drive two of the four available channels, using four SandForce SF-1200 controllers combined into a RAID-0 array to produce peak performance before reaching a collection of NAND flash components.

SandForce SF-1222TA3-SBC Processor

A key benefit to SandForce's SF-1200 architecture is that the SSD keeps all information on the NAND grid and removes the need for a separate cache buffer DRAM module by using the SandForce DuraClass technology. This results in a faster transaction, albeit at the expense of total storage capacity. SandForce SSDs also utilize over-provisioning technology, which allocates a portion of NAND for data storage and the remainder reserved for transaction and cache buffer space.

Comments

This thing really rocks. The 'real world' experience using a computer with one of these things inside of it must be sweet indeed. Can't afford one of them and may never be able to. But it's good to see that they're out there.

Any SSD will make you notice a super-boost in real world experience against HDDs. I'm sure you'll not notice a difference between controllers, but I'm not sure if the RevoDrive X2 could make THE difference.

You can expect the next generation of SandForce products in Q1 2011, but not sooner. This particular product, while being extremely fast, lacks TRIM support because of the RAID controller. In my opinion, you shouldn't buy an SSD without TRIM support. In this case however, there recovery time wouldn't be an issue unless you did constant fills.

Although this is an old post, I felt the need to clarify.TRIM is not needed for Revodrive X2 due to the garbage collecting algorithms built into SandForce. TRIM is a sloppy patch job on a problem that should of never existed and on any good drive will not be needed.